Worn out OS FP20 engine.

I suspect that my OS20FP engine piston is worn out. It probably has about a thousand flights on it. I took the cylinder and piston out of the case. Is there any easy test to tell if the engine is worn out? Like, how far should the piston go beyond the top of the liner?

Box them parts up and send 'em to Dan for his 'speriment.

See Ya

In the old days, we'd send the thing off for "rechroming". I haven't heard of anyone doing that in a while, but there are still people offering the service.

LAST EDITED ON Mar-17-04 AT 09:48 PM (CDT)
 
>In the old days, we'd send the thing off for "rechroming". I
>haven't heard of anyone doing that in a while, but there are
>still people offering the service.

Is collet sqeezing a viable fix? I have seen this service advertized. Where they squeeze the sleeve to gain a new fit.

I think Bob Oge still does chrome.

Hi Herman,

Is there a noticable performance drop that lead to your suspicion? Low compression, hard to start...etc.

I'm interested to know how to id a worn out engine as well.

Erratic run, will not needle, only runs in fast 2 stroke!

Never heard of collet squeezing, but I have heard of piston knurling, and piston "growing" (you heat it up in an oven to a particular temperature).

>I suspect that my OS20FP engine piston is worn out. It
>probably has about a thousand flights on it. I took the
>cylinder and piston out of the case. Is there any easy test
>to tell if the engine is worn out? Like, how far should the
>piston go beyond the top of the liner?
>

Is this an ABC (Or, in the OS case, ABN)? If so, it should not go beyond the top of the liner. You will notice, I said, "It shouldn't." I didn't say "it wouldn't." I have a new piston/liner for the 35 that I can push right on up through. So, take a look at it. Look at the piston and look at the liner on the inside? If you can see wear in the upper reaches of the inside of the cylinder, or, especially if you can see brass showing through, then the unit needs replacing.

Still, the proof is in the running. If it has lost compression, doesn't produce what it once did, it may be time for a quiet replacement. Chroming, by the way, will probably cost more than simply replacing, although a good chrome job should produce a better unit.

Incidentally, some engines run pretty well even when compression's dropped to the point where it's hard to start. Larry Driskill was lapping some of his 1/2-A combat engines to the point where they needed a drop of machine oil in the exhaust to start, but these things ran faster than anyone else's.

With hard-to-start Combat engines (usually upon landing after a lean run, not from being worn out), we carried a bottle of "suntan lotion" in the pitbox - suntan lotion being 50% STP and 50% Marvel Mystery Oil. Dump some in the exhaust and a really loose engine could be made to start.

LAST EDITED ON Mar-19-04 AT 11:27 PM (CDT)
 
Len,

I can easily push it 1/8" over the top of the liner. I believe the OS Liners are ABN not ABC. Do you think there is a durability difference between the two?

On Ebay right now, the seller Robair has many, many OS items new in package for sale, including a new piston and sleeve for the OS .20.

Hi william, How do you find the engine section in ebay? signed lost on ebay & feeling stupid,scott dinger:'(

Yes, go to ebay.com and on getting on site, it will ask you above, what are you looking for. Type in the auction number 3182315485 and Robair's auctin site will appear. Click on other items dealer has for sale, and get a complete list of all he is offering. William